Process and apparatus for spinning artificial silk from cuprammonium cellulose solutions



Dec. 5, 1939. K. FROWEIN ET 2,182,429

rnocsss AND APPARATUS FOR SPINNING ARTIFICIAL SILK mom CUPRAMMONIUM CELLULOSE sownous Filed April 1, 1937 Patented Dec. 5, 1939 PROCESS AND APPARATUS FOR SPINNING ARTIFICIAL SILK FROM CUPRAMP/IONI- v UM CELLULOSE SOLUTIONS Kurt Frowein, Wuppertal-Elberfeld, and Gotthard Bauriedel, Wuppertal-Barmen, Germany, and Viktor Elsaesser, Gozzano, Italy, assignors, by mesne assignments, to American Bemberg Corporation, New York, N. Y., a corporation of Delaware Application April 1, 1937, Serial No. 134,436

, In Germany April 4, 1936 8 Claims.

This invention relates to the manufacture of artificial silk from cuprammonium cellulose solutions by the funnel stretch spinning process and has for its object to provide an improved process for the manufacture of such artificial silk and an apparatus for carrying out this process.

In the manufacture of artificial silk from cuprammonium cellulose solutions by the funnel 10' stretch spinning process, it has been'discovered that small spinning funnels are in themselves capable of producing a much more uniform multiple thread strand than has been the case 7 with the hitherto usual comparatively large funnels, inthat the doubled threads are rendered uniform not only owing to the doubling but also because the individual multiple threads have a much more uniform consistency as regards purely physical properties as well as in regard to dyeing properties. In so far as in the case of the fine composite filaments variations in titer also occur, which are to be attributed to the known influences, the possibility is comparatively great that these deviations will compensate one another although there is also the occasional possibility of their being additive. In the final result, however, a much more uniform thread is obtained.

It has been further discovered that the operation of a small and narrow funnel, such as is adapted for fine filaments of from 10-25 denier thickness is much simpler and above all permits of a high spinning speed, which is not limited to even a withdrawal speed of 80 metres per minute,

3 while as is well known, in the case of the large older funnels 30 metres per minute withdrawal could only be exceeded with caution.

Moreover, it has further been proved to be a very important point that a thread comprising 40 two or more thread strands doubled or tripled is not simply obtained but onthe contrary the.

composite thread has quite a special structure,

inasmuch as the filaments of the multiple bundle,

during the carrying out of the'process, stick to one another and impart to the thread (and consequently to the article made from it) an entirely characteristic feel, differing it is true from a silk-like feel but on the other hand giving it to a certain degree a grainy structure, properties which are highly appreciated in these new products in the trade.

It is possible to produce such uniting or sticking together of the basic filaments by guiding the basic filaments together to form a composite thread strand at a very definite state .of the thread formation where adhesion of the individual filaments of the one basic thread strand with respect to the individual filaments of the neighbouring basic thread strand can still take place owing to the plasticity still present in the spun material while in the state in question. This state or the favourable moment is present after the multiple thread strands have already been produced in separate funnels, preformed, removed therefrom and separated from the bulk of the spinning water, i. e. preferably after the deviating bar or the first withdrawal roller or the like. The multiple threadstrands which are still only in contact with a small amount of precipitating water are then still sufficiently alkaline and in such a highly plastic state that on the multiple thread strands being guided together, adhesion of the multiple thread strands to one another takes place. This guiding together, however, must take place before the acidifying process acts, since thisacidifying process deprives the material of the thread of its high swelling as well as the necessary adhesiveness. During their further course, the multiple thread,

strands built up from the multiple filaments can then be continuously acidified, wound up and further worked up in the known manner.

The guiding together of the multiple filament bundles to form the composite thread bundle at the moment of the production process referred to can be effected under a certain degree ofpressure for assisting the adhesion. For this purpose specially constructed closing devices are employed. These closing devices which are more or less in the form of thread guides must be narrow and mayfor example be in the form of a slot or V-shaped. It is advantageous if the form of the thread guide is adapted to the size corresponding to the titer, in order that when ponent filament bundles are partly stuck togetherat their outer surfaces without on the other hand completely losing their original shape. The composite threads consequently have imparted to them on the whole an irregular multi-.lobular cross-section.

The conditions arising .during the guiding together of the component filament bundle are ex. plained more fully with reference to the accompanying drawing in which,

v Figure 1 shows a cross-section of an artificial silk thread having a thickness corresponding for example to denier and comprising 75 individual filaments each having a thickness corresponding to 1 denier.

Figure 2 is a longitudinal view of the thread shown in Figure 1,

Figure 3 shows a composite thread having a thickness corresponding to '75 denier but comprising three component threads or basic threads each having a thickness corresponding to 25 denier,

Figure 4 shows a thread which has been united to form a composite thread in accordance with the present invention,

Figure 5 shows diagrammatically the steps of the process, and

Figure 6 is a perspective view of an apparatus for carrying out the process.

Referring to Figures 1 and 2 of the drawing, the artificial silk thread which has been spun in accordance with the usual process in a single spinning funnel comprises 75 individual filaments, each having a thickness corresponding to 1 denier, so as to form a composite thread having a thickness corresponding to 75 denier. The individual capillary threads are distributed more or less regularly over the entire cross-section of the thread which is approximately circular. As will be seen from Figure 2, the individual capillary threads in the thread strand are stuck together at certain points so that a lightly reticulated sticking together or stiffening has taken place in the entire thread strand. This is the usual structure of the known artificial silk strand which has been produced by "the funnel spinning method from a cuprammonium cellulose solution.

In the composite thread shown in Figure 3, which is also of a thickness corresponding to 75 denier but isbuilt up from three component threads, each component thread comprises 25 separate filaments each having a thickness corresponding to 1 denier. The three basic threads lie closely adjacent to one another, particularly when twisting has taken place but they are not stuck together or stiffened. They are produced by combining three individual basic filament strands having a thickness corresponding to 25 denier, after being formed, to produce the composite thread having a thickness corresponding to 75 denier either after acidifying or even later.

In the composite thread shown in Figure 4, which is formed in accordance with the present invention and has a thickness corresponding to 75 denier, the cross-section is lobular and is seen to be composed of three parts corresponding to the three basic threads. The basic threads however are stuck together to a marked degree attheir points of contact so that the composite thread behaves on the outside as if it were a unitary structure, in spite of its comprising three separate parts. The sticking together of the individual filaments in the manner shown in Figure 2 takes place in the cross-section of Figure 4 not only within the component threads but also from the capillaries of the one component thread to the capillaries of the other component thread. This structure has come to pass in that three basic threads have been spun in separate funnels. After the component threads have left the funnels and have parted with the bulk of the spinning liquid while passing around the first deviating device and after they have been thus preformed and are still in 'a sufiiciently alkaline condition, they are united under light pressure in a narrow thread guide to form a composite thread and the composite thread is thereupon in continuous operation, acidified, wound up and then finished in the known manner.

, The carrying out of this process has also led to a special construction of the spinning device of the spinning machine. Instead of the old funnels, the number of which corresponds to the number of winding up points, a very large number of smallspinning funnels are arranged on the machine or on one side of the machine (when the machine is a double one), each of which is intended to produce only a thin component filament bundle having a thickness corresponding to from 10-25 denier. Then as desired, two or more such component threads are combined together in the manner above described and conducted to the common winding up point. For this purpose special devices are provided which as desired enable a two-ply, three-ply, four-ply etc., doubling of the thread to be effected.

In order to enable the largest possible number of small spinning funnels to be accommodated on the spinning machine or on the one side of the spinning machine, the spinning funnels. are arranged in a double row and are furthermore offset with respect to one another in order that the threads of the rear row will be able to pass conveniently between the gaps of the front row. This arrangement has been found to be advantageous and it has been proved that the geometric difference between the rear and front rows of funnels do not produce prejudicial results-in the finished product. According to the new process and the apparatus described, a very large number of spinning funnels it is true come pected results in the manufacture of artificial silk by the stretch spinning process which have only now actually become particularly apparent. It is intended in future to spin in the individual spinning funnels only a single titer, e. g. a titer corresponding to a thickness of 20 denier. Notwithstanding this. the market can be supplied with a comparatively large number and range of titers, in that namely a corresponding doubling of the component threads will be effected to form .a composite thread comprising two, three, four or five component thread bundles, so that the factory will be able, without any special changing over, to deliver finished artificial silks having a total titer of 20, 40, 60, etc. denier. The invention is thus capable of dealing with the varying requirements of the market in respect of fine titers in every respect without, as is well known, the delicate spinning machinery with the spin ning funnels having in any way tobe changed over. The importance of the invention will become particularly apparent when it is realised that for the production of different total titers it has hitherto been necesary to alter the individual spinning conditions in the stretching funnels in various points. Hitherto different total titers in the spinning funnel have called for different quantities of water, different water temperatures and in some cases difierent withdrawtificial silk filaments while the latter are still alkaline and somewhat adhesive so as to unite als and a lot more besides. Many of those skilled in the art actually found themselves compelled to provide for each individual total titer deviating from any other to any appreciable extent a special funnel construction and size. Those who did not wish to vary the shape and size of the funnel had tomake numerous compromises in chemical respects and were even then not in the position to adapt the spinning conditions in an ideal manner to the various total titers. Only the new process and the new apparatus permits, without changing over the water temperatures, quantities of water, or the funnel shapes and funnel sizes of a single funnelby means of which exclusively and alone component threads are spun of a thickness for example corresponding to 20 denier and suitable in all parts for the purpose being used under constant conditions at all times. Owing to the fact that only a unitary titer is spun and owing to the high stability of the spinning process, the uniformity and constancy of the viscosity, the temperature, the

water and solution pressure and the quantitiesof these substances can be uniformly regulated and controlled, in a manner which was never possible in the case of a multi-titer spinning process, where one is compelled to make compromises in view of the multiplicity of the titers.

The improvements have also the further advantage that in future the spinning machine plant can be operated with the same output or capacity, independently of what total titers are to be spun or called for. In this manner the capacity of the machine, i. e. the output in kilograms per unit of time, can be maintained constant independently of the desired titer, whereby a very good and uniform utilisation of the machine results.

Referring to the diagrammatic view shown in Figure 5 the filaments are withdrawn from the funnels I, I, I", 2, 2', 2 and so on. The filaments 3, 3", 4, and 5" are doubled together in the alkaline state in the thread guide members 6 and are then passed as a composite thread I through the fixed acidifying device 8 and the thread guide member 9. From there the composite thread passes through the thread guide device Ill to the reel II.

In the machine shown in Figure 6, the solution flows from a solution pipe I! and a branch pipe I8 to the spinning head I9, from which the filaments issue into the spinning funnels I, I, 2, the component thread bundles 3, 4, 5, passing around a glass roller I2 constituting the first deviating member and over deviating rods I3, M to the doubling bar on which is mounted the grooved closing rod I5, whereby the component thread bundles are brought together and united to form a triple thread which then passes around a second glass roller I6 and from there to the reel II where it is wound up. Between the closing rod I5 and the reel II the triple threads are acidified in known manner, e. g. by spraying as shown at 20, or by passing through an acidifying bath.

What we claim is:

l. A process for the production of artificial silk comprising forming a plurality of separate bundles of artificial silk filaments preliminarily by the cuprammonium stretch-spinning process in a stream of precipitating liquid, conducting the freshly spun bundles of filaments separately from one another around a deviating member to separate the precipitating liquid from the said threads, then bringing the said bundles of arthe said bundles of filaments to form a composite thread, and thereafter acidifying the composite thread.

2. A process for the production of artificial silk comprising forming a plurality of separate bundles of artificial silk filaments preliminarily by the cuprammonium stretch-spinning process in a stream of precipitating liquid, conducting the freshly spun bundles of filaments separately from one another around a deviating member to separate the precipitating liquid from the said threads, guiding together the said bundles of artificial silk while the latter are still somewhat adhesive, applying a light pressure to the filament bundles while being united to form a composite thread, and thereafter acidifying the composite thread.

3. A process for the production of artificial silk comprising forming a plurality of separate bundles of artificial silk filaments preliminarily by the cuprammonium stretch-spinning process in a stream of precipitating liquid, each of said bundles having a thickness lying within a range correspo-nding to 10 to 25 denier, inclusively, conducting the bundles of threads separately in a path whereby separation of the precipitating liquid from the said threads takes place, guiding together the said bundles of artificial silk filaments while the latter still possess a certain amount of adhesiveness so as to unite the said bundles of filaments to form a composite thread, and thereafter acidifying the composite thread.

4. An artificial silk stretch spinning apparatus for producing threads, comprising a precipitating apparatus, a plurality of spinnerettes arranged to provide a plurality of individual threads arranged in separate groups, a plurality of funnels, each of which is disposed to receive one of said groups of filaments, means toguide said groups of filaments separately from said funnels in a path whereby precipitating liquid is separated from said groups o f'threads, a thread uniting means to receive said threads from said guiding device and cause said separate groups of' thread to form a composite thread, and means to acidify said thread after passage through said thread uniting means.

5. An artificial silk stretch spinning apparatus for producing threads, comprising a precipitating apparatus, a plurality of spinnerettes arranged to provide a plurality bf individual threads arranged in separate groups, a plurality of funnels, each of which is disposed to receive one of said groups of filaments, means to guide said groups of filaments separately from said funnels in a path whereby precipitating liquid is separated from said groups of threads, a thread uniting means to receive said threads from said guiding device and cause said separate groups of thread to .form a composite thread, said thread uniting means comprising a narrow slot through which the composite thread is forced to pass, and means to acidify said thread after passage through said thread uniting means.

6. An artificial silk stretch spinning apparatus for producing threads, comprising a precipitating said groups of threads; a-thread uniting means to, receive said threads from said guiding device while said threads are in a plastic state and cause said separate groups of threads to form a composite thread, means to acidify said composite thread, and means to collect said thread.

'7. An artificial silk stretch spinning apparatus for producing threads, comprising a precipitating apparatus, a plurality of spinnerettes arranged to provide a plurality of individual threads arranged in separate groups, a plurality of funnels, each of which is disposed to receive one of said groups of threads, means to guide said groups of threads separately from said funnels in a path whereby precipitating liquid is separated from said groups of threads, a thread uniting device comprisinga narrow slot to receive said threads from said guiding device while said threads are in a plastic state, means to apply pressure to said threads as they pass to said thread uniting means and cause said groups of threads to form a composite thread, means to acidify said composite thread after passage through said uniting means, and means to collect said thread.

8. An artificial silk stretch spinning apparatus for producing threads, comprising a precipitating apparatus, a plurality of spinning funnels arranged in two rows and staggered with respect to one another, a spinnerette disposed within each of said funnels for spinning a plurality of individual threads through each of said funnels, means to guide said groups of threads separately from said funnels in a path whereby precipitating liquid is separated from said groups of threads, a thread uniting device to receive a plurality of said groups of threads from said guiding device while said threads are in a plastic state and cause said separate groups of threads to form composite threads, means to acidify said composite threads, and means to collect said threads.

KURT FROWEIN. GOTTI-IARD BAURIEDEL. VIKTOR ELSAESSER.

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